This application describes and claims certain improvements in the basic electrochemical cell disclosed in United States patent 3,791,871.
The basic mechanism of the cell described in the aforementioned patent is incorporated by reference in this application. Briefly, the cell utilizes a reactive metal anode highly reactive with a aqueous electrolyte and spaced from the cathode by an electrically insulating film which forms naturally on the anode in the presence of water. This thin film permits the cathode to be placed in direct contact with the anode. The resulting reduction in the anode-cathode spacing to a thickness no greater than the thickness of this film greatly reduces the I.sup.2 R losses which would otherwise be present and results in increased power output and energy density. The anode and cathode operate in an aqueous electrolyte which supports the beneficial electrochemical reaction. As disclosed in co-pending U.S. Pat. application Ser. No. 443,905, the cathode is beneficially formed of an open-mesh metallic screen contoured to contact the anode over substantially the entire operating surface.
During operation of the cell, molarity of the electrolyte increases with a resulting decrease in power output. Further, excess heat must be removed from the electrolyte which would otherwise result in a loss of efficiency. Likewise, depolarization of the cell must be accomplished by removal of hydrogen gas evolved at the cathode. Accordingly, the electrolyte is normally pumped through the cell in order to remove heat, bring in additional oxidant to maintain desired molarity and remove hydrogen. The use of mechanical pumps and heat exchangers for this purpose are cumbersome, consume power and generate noise, all of which are undesirable.